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Blue Mountain buckwheat, strict buckwheat

Thurber eriogonum, Thurber's buckwheat, Thurber's wild buckwheat

Habit Herbs, erect, loosely to densely matted, not scapose, 1–5 × 1–10 dm, tomentose or glabrous. Herbs, spreading, annual, 0.5–4 dm, glabrate, glabrous or sparsely glandular, greenish, grayish, or reddish.
Stems

spreading to erect, with or without persistent leaf bases, up to 1/4 height of plant;

caudex stems absent or spreading to matted;

aerial flowering stems erect to spreading, slender, solid, not fistulose, 1–3 dm, tomentose or glabrous.

caudex absent;

aerial flowering stems erect, solid, not fistulose, 0.3–1 dm, often sparsely tomentose and glandular proximally.

Leaves

basal, 1 per node;

petiole rarely twisted or curled, 1–6 cm, mostly tomentose;

blade elliptic to ovate, 0.5–2.5(–4) × (0.3–)0.5–1.5 cm, lanate, tomentose to floccose on both surfaces, sometimes sparsely tomentose to floccose and greenish or floccose to subglabrous or glabrous adaxially, margins plane.

basal;

petiole 1–3 cm;

blade oblong to narrowly ovate, 0.8–4.5 × 0.5–3 cm, densely white-tomentose abaxially, floccose or glabrous and greenish adaxially, margins often crenulate.

Inflorescences

umbellate-cymose to cymose, 1–20 × 3–25 cm;

branches dichotomous, tomentose to floccose or less often glabrous;

bracts 3, scalelike, triangular, 1–3 mm.

cymose, mostly diffuse, 5–30 × 5–50 cm;

branches sparsely glandular to glabrate or glabrous;

bracts 3, scalelike, 1–2.5 × 1–2.5 mm.

Peduncles

absent.

erect, straight, capillary, 0.5–2.5 cm, glabrous and glandular-puberulent distally.

Involucres

1 per node, rarely 2–5 per cluster, narrowly turbinate to turbinate-campanulate, 4–6 × 1.5–5 mm, tomentose or glabrous;

teeth 5, erect, 0.5–1.3 mm.

broadly turbinate, 1.8–2 × 1.8–2 mm, minutely glandular-puberulent;

teeth 5, erect, 0.4–0.6 mm.

Flowers

3–5(–6) mm;

perianth yellow or white to rose or purple, glabrous;

tepals connate proximally, dimorphic, those of outer whorl elliptic to nearly orbiculate, 2–3 × 2–3 mm, those of inner whorl oblanceolate to oblong, 3–4 × 1–2 mm;

stamens included to slightly exserted, 2–5 mm;

filaments pilose proximally.

1–1.7 mm;

perianth white with greenish or reddish midribs, becoming red, glandular-puberulent with a tuft of long white hairs adaxially;

tepals dimorphic, those of outer whorl broadly pandurate or flabellate, those of inner whorl oblanceolate;

stamens included, 0.7–1.2 mm;

filaments mostly glabrous.

Achenes

light brown to brown, 3–3.5 mm, glabrous.

brown to black, usually lenticular, 0.6–0.8 mm, glabrous.

2n

= 40.

Eriogonum strictum

Eriogonum thurberi

Phenology Flowering year-round.
Habitat Sandy flats, washes, and slopes, saltbush, greasewood, and creosote bush communities, oak, pinyon and/or juniper woodlands, (montane conifer woodlands in Mexico)
Elevation 100-1200 m (300-3900 ft)
Distribution
from FNA
CA; ID; MT; NV; OR; WA
[WildflowerSearch map]
[BONAP county map]
from FNA
AZ; CA; NM; Mexico (Baja California, Sonora)
[WildflowerSearch map]
[BONAP county map]
Discussion

Varieties 4 (4 in the flora).

Eriogonum strictum, E. niveum, and E. ovalifolium form a complex of closely related species differing in leaf, inflorescence branching, and flower features. Variety proliferum appears to be the basal entity of the complex, approaching both E. niveum and E. ovalifolium var. pansum in its pubescence and branching pattern. Also, specimens of var. proliferum are sometimes difficult to differentiate from E. nudum var. oblongifolium. Careful observation, though, will permit well-made collections to be easily distributed among the individual species. An alternative taxonomy is to reduce all of the taxa to E. ovalifolium and recognize a series of subspecies and varieties. It is possible that additional study will show that E. strictum is sufficiently distinct from its tomentose to floccose counterparts to justify recognition of E. proliferum. In that case, both var. anserinum and var. greenei would be assigned to the latter species. Or, one could follow C. L. Hitchcock et al. (1955–1969, vol. 2) and recognize subsp. strictum as distinct from subsp. proliferum, with the latter consisting of varieties proliferum, anserinum, and greenei.

Members of the Eriogonum strictum are food plants for the Bauer’s dotted-blue butterfly (Euphilotes baueri).

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Eriogonum thurberi is common to abundant but rarely weedy in northwestern Mexico, southern California (Inyo, Los Angeles, Orange, Riverside, San Bernardino, and San Diego counties), and southern Arizona (Cochise, Gila, Graham, Maricopa, Mohave, Pima, Pinal, Santa Cruz, and Yavapai counties). It just enters New Mexico (Grant County). It and E. thomasii are the annual members of the E. cernuum complex typically found on the Mojave and Sonoran deserts, with E. thurberi extending farther to the east and E. thomasii farther to the north. The two occasionally grow together.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Key
1. Inflorescence branches glabrous
var. strictum
1. Inflorescence branches tomentose to floccose
→ 2
2. Perianths yellow
var. anserinum
2. Perianths white to rose or purple
→ 3
3. Leaf blades grayish-tomentose to floccose on both surfaces, or greenish-tomentose to floccose adaxially
var. proliferum
3. Leaf blades densely whitish-lanate to tomentose on both surfaces
var. greenei
Source FNA vol. 5, p. 317. FNA vol. 5, p. 403.
Parent taxa Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Eucycla Polygonaceae > subfam. Eriogonoideae > Eriogonum > subg. Ganysma
Sibling taxa
E. abertianum, E. acaule, E. alatum, E. aliquantum, E. allenii, E. alpinum, E. ammophilum, E. ampullaceum, E. androsaceum, E. anemophilum, E. angulosum, E. annuum, E. apiculatum, E. apricum, E. arborescens, E. arcuatum, E. aretioides, E. argillosum, E. argophyllum, E. arizonicum, E. artificis, E. atrorubens, E. baileyi, E. batemanii, E. bicolor, E. bifurcatum, E. brachyanthum, E. brachypodum, E. brandegeei, E. breedlovei, E. brevicaule, E. butterworthianum, E. caespitosum, E. capillare, E. cernuum, E. chrysops, E. cinereum, E. cithariforme, E. clavatum, E. clavellatum, E. codium, E. collinum, E. coloradense, E. compositum, E. concinnum, E. congdonii, E. contiguum, E. contortum, E. correllii, E. corymbosum, E. covilleanum, E. crocatum, E. cronquistii, E. crosbyae, E. cusickii, E. darrovii, E. dasyanthemum, E. davidsonii, E. deflexum, E. deserticola, E. desertorum, E. diatomaceum, E. diclinum, E. divaricatum, E. douglasii, E. eastwoodianum, E. effusum, E. elatum, E. elegans, E. elongatum, E. ephedroides, E. eremicola, E. eremicum, E. ericifolium, E. esmeraldense, E. evanidum, E. exaltatum, E. exilifolium, E. fasciculatum, E. flavum, E. fusiforme, E. giganteum, E. gilmanii, E. glandulosum, E. gordonii, E. gossypinum, E. gracile, E. gracilipes, E. gracillimum, E. grande, E. greggii, E. gypsophilum, E. havardii, E. heermannii, E. helichrysoides, E. hemipterum, E. heracleoides, E. hieracifolium, E. hirtellum, E. hirtiflorum, E. hoffmannii, E. holmgrenii, E. hookeri, E. howellianum, E. hylophilum, E. incanum, E. inerme, E. inflatum, E. intrafractum, E. jamesii, E. jonesii, E. kelloggii, E. kennedyi, E. kingii, E. lachnogynum, E. lancifolium, E. latens, E. latifolium, E. lemmonii, E. leptocladon, E. leptophyllum, E. libertini, E. lobbii, E. loganum, E. lonchophyllum, E. longifolium, E. luteolum, E. maculatum, E. mancum, E. marifolium, E. mensicola, E. microthecum, E. mitophyllum, E. mohavense, E. molestum, E. mortonianum, E. multiflorum, E. natum, E. nealleyi, E. nervulosum, E. nidularium, E. niveum, E. nortonii, E. novonudum, E. nudum, E. nummulare, E. nutans, E. ochrocephalum, E. ordii, E. ostlundii, E. ovalifolium, E. palmerianum, E. panamintense, E. panguicense, E. parishii, E. parvifolium, E. pauciflorum, E. pelinophilum, E. pendulum, E. pharnaceoides, E. plumatella, E. polycladon, E. polypodum, E. prattenianum, E. prociduum, E. pulchrum, E. pusillum, E. pyrolifolium, E. racemosum, E. reniforme, E. ripleyi, E. rixfordii, E. robustum, E. rosense, E. roseum, E. rotundifolium, E. rubricaule, E. rupinum, E. salicornioides, E. saxatile, E. scabrellum, E. scopulorum, E. shockleyi, E. siskiyouense, E. smithii, E. soliceps, E. soredium, E. spathulatum, E. spectabile, E. spergulinum, E. sphaerocephalum, E. subreniforme, E. suffruticosum, E. temblorense, E. tenellum, E. ternatum, E. terrenatum, E. thomasii, E. thompsoniae, E. thornei, E. thurberi, E. thymoides, E. tiehmii, E. tomentosum, E. trichopes, E. tripodum, E. truncatum, E. tumulosum, E. twisselmannii, E. umbellatum, E. ursinum, E. vestitum, E. villiflorum, E. vimineum, E. viridescens, E. viridulum, E. viscidulum, E. visheri, E. watsonii, E. wetherillii, E. wootonii, E. wrightii, E. zionis
E. abertianum, E. acaule, E. alatum, E. aliquantum, E. allenii, E. alpinum, E. ammophilum, E. ampullaceum, E. androsaceum, E. anemophilum, E. angulosum, E. annuum, E. apiculatum, E. apricum, E. arborescens, E. arcuatum, E. aretioides, E. argillosum, E. argophyllum, E. arizonicum, E. artificis, E. atrorubens, E. baileyi, E. batemanii, E. bicolor, E. bifurcatum, E. brachyanthum, E. brachypodum, E. brandegeei, E. breedlovei, E. brevicaule, E. butterworthianum, E. caespitosum, E. capillare, E. cernuum, E. chrysops, E. cinereum, E. cithariforme, E. clavatum, E. clavellatum, E. codium, E. collinum, E. coloradense, E. compositum, E. concinnum, E. congdonii, E. contiguum, E. contortum, E. correllii, E. corymbosum, E. covilleanum, E. crocatum, E. cronquistii, E. crosbyae, E. cusickii, E. darrovii, E. dasyanthemum, E. davidsonii, E. deflexum, E. deserticola, E. desertorum, E. diatomaceum, E. diclinum, E. divaricatum, E. douglasii, E. eastwoodianum, E. effusum, E. elatum, E. elegans, E. elongatum, E. ephedroides, E. eremicola, E. eremicum, E. ericifolium, E. esmeraldense, E. evanidum, E. exaltatum, E. exilifolium, E. fasciculatum, E. flavum, E. fusiforme, E. giganteum, E. gilmanii, E. glandulosum, E. gordonii, E. gossypinum, E. gracile, E. gracilipes, E. gracillimum, E. grande, E. greggii, E. gypsophilum, E. havardii, E. heermannii, E. helichrysoides, E. hemipterum, E. heracleoides, E. hieracifolium, E. hirtellum, E. hirtiflorum, E. hoffmannii, E. holmgrenii, E. hookeri, E. howellianum, E. hylophilum, E. incanum, E. inerme, E. inflatum, E. intrafractum, E. jamesii, E. jonesii, E. kelloggii, E. kennedyi, E. kingii, E. lachnogynum, E. lancifolium, E. latens, E. latifolium, E. lemmonii, E. leptocladon, E. leptophyllum, E. libertini, E. lobbii, E. loganum, E. lonchophyllum, E. longifolium, E. luteolum, E. maculatum, E. mancum, E. marifolium, E. mensicola, E. microthecum, E. mitophyllum, E. mohavense, E. molestum, E. mortonianum, E. multiflorum, E. natum, E. nealleyi, E. nervulosum, E. nidularium, E. niveum, E. nortonii, E. novonudum, E. nudum, E. nummulare, E. nutans, E. ochrocephalum, E. ordii, E. ostlundii, E. ovalifolium, E. palmerianum, E. panamintense, E. panguicense, E. parishii, E. parvifolium, E. pauciflorum, E. pelinophilum, E. pendulum, E. pharnaceoides, E. plumatella, E. polycladon, E. polypodum, E. prattenianum, E. prociduum, E. pulchrum, E. pusillum, E. pyrolifolium, E. racemosum, E. reniforme, E. ripleyi, E. rixfordii, E. robustum, E. rosense, E. roseum, E. rotundifolium, E. rubricaule, E. rupinum, E. salicornioides, E. saxatile, E. scabrellum, E. scopulorum, E. shockleyi, E. siskiyouense, E. smithii, E. soliceps, E. soredium, E. spathulatum, E. spectabile, E. spergulinum, E. sphaerocephalum, E. strictum, E. subreniforme, E. suffruticosum, E. temblorense, E. tenellum, E. ternatum, E. terrenatum, E. thomasii, E. thompsoniae, E. thornei, E. thymoides, E. tiehmii, E. tomentosum, E. trichopes, E. tripodum, E. truncatum, E. tumulosum, E. twisselmannii, E. umbellatum, E. ursinum, E. vestitum, E. villiflorum, E. vimineum, E. viridescens, E. viridulum, E. viscidulum, E. visheri, E. watsonii, E. wetherillii, E. wootonii, E. wrightii, E. zionis
Subordinate taxa
E. strictum var. anserinum, E. strictum var. greenei, E. strictum var. proliferum, E. strictum var. strictum
Synonyms E. cernuum subsp. thurberi, E. cernuum subsp. viscosum
Name authority Bentham: Trans. Linn. Soc. London 17: 414. (1836) Torrey: in W. H. Emory, Rep. U.S. Mex. Bound. 2(1): 176. (1859)
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